Okay, before I get flamed...
DSD is not DHs bio-child, but he has been in her life from day 1. We don't have any other children, and don't intend to.
DH & I have been together 9 years. DH carried on contact with his DSD after break-up and she has always been with us at least 50% of time. DSD 17F has now lived with us full time for last 2 years, after her relationship with bio-mum broke down and she asked to live with us. She is now becoming increasingly difficult, refusing to keep room tidy, breaking items, leaving front door open when going out, not bringing pots down, not attending family social events, and basically not doing ANYTHING for herself. Think "If I don't bother someone else will do it for me". No, she isn't depressed, she is more than happy to do things with other people, but is treating our house with no respect.
She is constantly refusing to do social things with us and DH's family, but will go out with her bio-mum to events, which makes DHs family feel awful as they have been in her life for 17 years.
We receive 0 financial support from either parent, and have been told we can't claim child support as bio-mum is already doing this, so we are financially struggling to support her too.
AIBU to sit down this weekend and tell DH that either she goes or I do? DH works away 5 days a week, so I bear the brunt of everything, and I can't do it any more.